That does seem plausible, since that looks more like a tin of salmon than a tin of herring to me. Still, questionable as to whether it was really in the tin, and if not, the nature of the tin is a moot point.

The true herrings (Clupeidae) are soft-finned fishes wholly lacking spines, with one short dorsal fin, deeply forked tails, ventral fins situated on the abdomen far behind the pectorals, teeth small or lacking in adults

Maybe not a herring then...

One reason it looks freaky is that that appears to be the lower jaw of whatever it is, but they've positioned it so that you assume it's an upper jaw. It does look like the cooked lower jaw of some sort of fish, so it's plausible that it was really found in a can of herring, or that somebody had some fish parts lying around and decided to pretend it had been. I reckon the latter is still more likely, especially if it isn't the same type of fish as in the tin.